Level Error Calculation for Spectrum Analyzers

Level or power measurement of especially modulated signals using spectrum analyzers is becoming more and more important . Whereas the first choice in terms of accuracy for power measurement of any carrier (modulated or non-modulated) is a power meter, power measurement of spurious or in the adjacent channel of a transmission system needs a selective power meter with high dynamic range. A power meter, however, is a non-selective device with limited dynamic range and is not appropriate for these types of measurements. The first choice is a spectrum analyzer because of its versatile use as a general-purpose instrument. Compared to a power meter its power measurement accuracy is worse. In general this can be overcome by substitution methods using a power meter, an attenuator and a signal generator. But substitution is time-consuming and requires more investment in test equipment than a single instrument. Therefore it is most important to have a spectrum analyzer like the FSE, which can fulfill at least most of the requirements in terms of measurement accuracy.